Effect of urbanisation on feces deposited across natural urban forest fragments

Seed dispersal has been an indispensable ecosystem process mediated by biotic and abiotic vectors. Animal-mediated seed dispersal, such as endozoochory, has supported plants to sustain and establish in new locations. However, increasing urbanisation make feces deposition sites as a detrimental factor for the successful seed establishment. In this regard, this study explores the deposition of feces across the eight natural urban forest fragments with varying urbanisation rates in Tokyo-Yokohama, one of the largest urban agglomerations in the world. Paved roads within the forest fragments were surveyed for feces deposition and the urbanisation rate was estimated for all the studied sites. We found 1381 feces deposited on the paved roads, with the highest in ‘Sagamihara Chuo green space’ (n = 673) and the second highest in ‘Yokohama National University’ forest area (n = 488). This study revealed a strong influence of urbanisation on feces deposition in the forest fragments. Birds were the prominent group of animals that deposited feces on paved roads. This is the first study systematically showing the influence of urbanisation on transforming the seed dispersal service by animals into potential low services due to seed wastage in feces deposited on paved roads. Urban forest management needs to consider the impact of urbanisation on not just species diversity, but the interactions and services provided by species.